The present invention relates to chemical solvating, degreasing, stripping and cleaning agents. More particularly, this invention relates to cleaning and solvating compositions containing dichloroethylene and six carbon length hydrofluoroethers and/or other agents that improve and enhance the properties of the original mixture.
The present invention was made in response to concerns with ozone depleting materials, and toxicity concerns with non-ozone depleting chlorinated materials. In September 1987, the United States and 22 other countries signed the Montreal Protocol on Substances that Deplete the Ozone Layer (the “Protocol”). The Protocol called for a freeze in the production and consumption of ozone depleting chemicals (“ODP's” or “ODC's”) by the year 2000 for developed countries and 2010 for developing countries. In 1990 the United States enacted the Clean Air act mandating that the use of ozone depleting chemicals be phased out by the year 2000. In September 1991, the U.S. Environmental Protection Agency announced that ozone layer depletion over North America was greater than expected. In response to this announcement, President George H. W. Bush issued an executive order accelerating the phase-out of the production of ozone depleting materials to Dec. 31, 1995. More than 90 nations, representing well over 90% of the world's consumption of ODP's, have now agreed to accelerate the phase-out of production of high ozone depleting materials to Dec. 31, 1995 for developed countries and Dec. 31, 2005 for developing countries pursuant to the protocol.
Historically fluorine and chlorine based solvents were widely used for degreasing, solvating, solvent cleaning, aerosol cleaning, stripping, drying, cold cleaning, and vapor degreasing applications. In the most basic form the cleaning process required contacting a workpiece with the solvent to remove an undesired material, soil or contaminant. In solvating applications these materials were added to dissolve materials in such applications as adhesive or paint formulations.
Cold cleaning, aerosol cleaning, stripping and basic degreasing were simple applications where a number of solvents were used. In most of these processes the soiled item was immersed in the fluid, sprayed with the fluid, or wiped with cloths or similar objects that had been soaked with the fluid. The soil was removed and the item was allowed to air dry.
Drying, vapor degreasing and/or solvent cleaning consisted of exposing a room temperature workpiece to the vapors of a boiling fluid or directly immersing the workpiece in the fluid. Vapors condensing on the workpiece provided a clean distilled fluid to wash away soils and contaminants. Evaporation of the fluid from the workpiece provided a clean item similar to cleaning the same in uncontaminated fluid.
More difficult cleaning of difficult soils or stripping of siccative coatings such as photomasks and coatings required enhancing the cleaning process through the use of elevated fluid temperatures along with mechanical energy provided by pressure sprays, ultrasonic energy and or mechanical agitation of the fluid. In addition these process enhancements were also used to accelerate the cleaning process for less difficult soils, but were required for rapid cleaning of large volumes of workpieces. In these applications the use of immersion into one or more boiling sumps, combined with the use of the above mentioned process enhancements was used to remove the bulk of the contaminant. This was followed by immersion of the workpiece into a sump that contained freshly distilled fluid, then followed by exposing the workpiece to fluid vapors which condensed on the workpiece providing a final cleaning and rinsing. The workpiece was removed and the fluid evaporated. Vapor degreasers suitable in the above-described process are well known in art.
In recent years the art was continually seeking new fluorocarbon based mixtures which offered similar cleaning characteristics to the chlorinated and chlorofluorocarbon (CFC) based mixtures and azeotropes. In the early 1990's materials based on the compounds of hydrochlorofluorocarbons (HCFC) began to appear. Three molecules in particular 1,1-dichloro-1-fluoro ethane (HCFC-141b), dichloro trifluoro ethane (HCFC-123), and dichloro pentafluoro propane (HCFC-225) were proposed as replacements for methyl chloroform and CFC blends. As more highly fluorinated materials these materials were less ozone depleting than current ODP's however these materials were weaker solvents and in order to properly clean required the use of co-solvents through the use of blends and azeotropes. Later toxicity studies performed on these materials, however, showed them to have unacceptable character for broad commercial use in cleaning applications. Consequently HCFC-123 was immediately limited in cleaning use, and HCFC-141b was phased out in the U.S. by Apr. 1, 1997. HCFC-225 is still used, however the material is scheduled for phase out by the Clean Air Act after the year 2010. Toxicity concerns with HCFC-225 exist to some users and the recommended commercial exposure level of blends of the various isomers of the material is 100 ppm.
In the mid 1990's another art emerged through the use of brominated solvents similar in structure to ozone depleting chlorofluorocarbons. Three molecules were proposed as viable products to replace ODP's, bromochloromethane (BCM), isopropyl bromide (iBP) and n-propyl bromide (nPB). Although all three materials have excellent cleaning solvency for many soils, the first two materials BCM and iBP have been eliminated due to potential health risks. The third candidate nPB has undergone a number of toxicity tests with the results being inconclusive. Currently most reputable producers of nPB are indicating a safe 8-hour TLV level of 25 ppm, which is of some concern to some users.
The art in the mid 1990's changed as aqueous and semi-aqueous materials became the major choice of replacement for ODP's. The shift to these materials however had two drawbacks for some users. First was the requirement for new cleaning apparatus and machinery capable of handling and drying water. The second was the fact that certain niche applications in the marketplace could not tolerate the use of water in the cleaning process due to damage to the workpiece. This damage was caused by either incompatibility of water with the workpiece, or residual water remaining on the workpiece due to the geometry of the workpiece. This second factor resulted in the art shifting to processes cleaning with solvents and either rinsing with volatile flammable solvents such as acetone hexane, cyclohexane and isopropanol, or rinsing with highly fluorinated materials called perfluorocarbons (PFC's).
These PFC rinsing agents were investigated by some users. Other solvents such as low molecular weight alcohols, ketones and alkanes, were also evaluated since they provided users with acceptable rinsing and cleaning, however they were flammable and concerns were raised about their use in production applications. Systems that operated with these inexpensive solvents were very expensive and required explosion-proof machinery and buildings. Perfluorocarbons were deemed to be viable replacements in that they could potentially be operated in inexpensive vapor degreasing equipment such as was used for CFC's. Additionally these materials were inert, inflammable, and had very low toxicity. However, being inert these materials had no solvency, i.e., they did not dissolve the soils they were meant to remove from the workpieces, and were found to be poor cleaning materials. Other perceived drawbacks with these rinsing agents were that they were extremely expensive and required the use of modified vapor degreasers. Later work conducted by the U.S. EPA deemed PFC's to be unacceptable materials due to the fact that they had huge global warming potentials and would remain in the environment for thousands of years.
The art then evolved today to seeking materials for these specialty applications that required PFC like materials that had lower global warming potentials. Highly fluorinated materials such as hydrofluorocarbons (HFC's) and hydrofluoroethers (HFE's) and other highly fluorinated compounds are the result of the most recent disclosures. Like PFC, HFC's and HFE's exhibit the same characteristics, with the exception they are slightly less expensive than PFC's but are still orders of magnitude more expensive than CFC's and chlorinated solvents. Primarily used as rinsing, drying and inserting agents these materials exhibit poor solvency for the soils commonly encountered in most cleaning applications, and will require the use of solvent blends, co-solvent systems, and azeotrope like blends in order to effectively clean.
As a replacement for CFC compounds and mixtures in cleaning applications, the use of highly fluorinated materials HFE's or HFC's have been described in a number of patents in combination with dichloroethylenes and other halogenated solvents. Most of the disclosed blends contain mixtures with highly fluorinated materials containing two to six carbon atoms. In industrial practice blends containing little or no dichloroethylene or halogenated solvents are only useful in cleaning light oils and particulates since the highly fluorinated materials have little cleaning efficacy. Mixtures having dichloroethylene or halogenated solvents as the major component are known to be more effective in cleaning a broader array of soils and thus are preferred.
The use of an HFC, decafluoropentane,(a 5 carbon highly fluorinated material) is disclosed in U.S. Pat. No. 5,196,137. This patent discloses the binary azeotrope of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC-4310mee) with cis- or trans-1,2-dichloroethylene. U.S. Pat. No. 5,064,560 discloses the ternary azeotropes of HFC-4310 mee with trans-1,2-dichloroethylene and with methanol or ethanol. U.S. Pat. No. 5,759,986 discloses the ternary azeotrope of HFC-4310 mee with trans-1,2-dichloroethylene (trans DCE) and cyclopentane, and the quaternary azeotrope of the three materials plus methanol. All the above listed mixtures produce non-flammable, azeotrope-like mixtures with the highest claimed level of dichloroethylene in any of the patents being 50%.
The use of an HFE is disclosed in a number of patents. U.S. Pat. No. 5,827,812 discloses a number of binary azeotrope-like mixtures with two isomers of perfluorobutyl methyl ether (HFE-7100), a highly fluorinated 5 carbon molecule. Included in disclosed binary azeotropes are trans and cis 1,2-dichloroethylene, methylene chloride, nPB and HCFC-225. U.S. Pat. No. 6,008,179 discloses binary azeotrope-like mixtures between HFE-7100 and methanol, ethanol, 1-propanol, 2-butanol, isobutanol, and tert-butanol. In addition it names ternary azeotrope-like mixtures between HFE-7100, trans DCE and methanol, ethanol, 1-propanol, 2-propanol (IPA), and tert-butanol. Further the patent discloses other ternary azeotrope-like mixtures between HFE-7100, HCFC-225 (a hydrofluorinated-chlorinated solvent) and methanol or ethanol. Most of the combinations with HFE-7100 described in these patents are non-flammable and show acceptable flammability character when high levels of HFE-7100 are present. Ternary azeotrope like combinations with halogenated solvents are not as flammable but like HFC-4310, form azeotrope-like mixtures at dichloroethylene levels of near and/or less than 50 wt % of the mixture.
The use of another HFE material, perfluorobutyl ethyl ether (HFE-7200, a six carbon highly fluorinated material) is described U.S. Pat. Nos. 5,814,595, 6,235,700 and in 6,288,018. These patents describe a number of binary azeotrope-like mixtures with two isomers of the perfluorobutyl ethyl ether. All binary combinations are shown to be flammable with the exception of azeotropes with the following halogenated solvents: hexafluoro-2-propanol, 1,2-dichloropropane and trans DCE. The combination with trans DCE is the most interesting aspect of this patent because the material forms an azeotrope-like product at 62.7 to 68.8 wt % trans DCE depending on the HFE-7200 isomer mixture.
The family of HFE materials are fully described in U.S. Pat. No. 6,291,417. This patent teaches the use of highly fluorinated ethers described in general as alkoxy-substituted perfluorocompounds in combination at least one co-solvent selected from a group of multiple chemical families. The patent claims that the fluorinated ether component must be at least 30% by weight of the composition and more preferred to be at least 50% of the mixture (a majority of the mixture) and most preferred to be greater than 60%.
Dichloroethylene compositions are described in U.S. Pat. No. 5,851,977. The patent discloses the use of 1,2-dichloroethylene in combination with a specific group of selected 3 and 4 carbon halogenated alkanes and alcohols. In the described patent the halogenated alkanes and alcohols are used to retard the flash point of the dichloroethylene.
U.S. Pat. Nos. 5,654,129 and 5,902,412 describe non-azeotrope mixtures of dichloroethylene and perchloroethylene that can be used to clean photographic films and other general substrates. The perchloroethylene is used in the formulation to retard the flash point of the dichloroethylene.
There currently is a need for azeotrope or azeotrope like compositions that are able to clean difficult soils and fluxes that are not effectively cleaned today by current art. Preferably these compositions would be non-flammable, effective cleaning, have little or no ozone depletion potential and have relatively short atmospheric lifetime so that they do not contribute to global warming.
The present invention provides a solvent mixture which can be used in solvating, vapor degreasing, photoresist stripping, adhesive removal, aerosol, cold cleaning, and solvent cleaning applications including defluxing, dry-cleaning, degreasing, particle removal, metal and textile cleaning. Non-limiting examples of the soils and contaminants that are removed by the composition of the present invention are oil, grease, coatings, flux, resins, waxes, rosin, adhesives, dirt, fingerprints, epoxies, polymers, and other common contaminants found in the art.
The present cleaning and solvating compositions comprise dichloroethylene compounds and alkoxy-substituted perfluoro compounds that contain six carbon atoms (HFE6C). The compositions also include highly fluorinated materials to retard flammability and/or other enhancement agents that improve and enhance the properties of the original mixture. The addition of these agents to the composition will modify the physical and/or cleaning characteristics of the dichloroethylene/HFE6C mixture to accomplish its desired cleaning or solvating task. The highly fluorinated material is any fluorinated hydrocarbon material in which the number of fluorine atoms exceeds the number of hydrogen atoms on the molecule. The enhancement agents are one or more of the following materials: alcohols, esters, ethers, cyclic ethers, ketones, alkanes (including cyclic alkanes), aromatics, amines, siloxanes, terpenes, dibasic esters, glycol ethers, pyrollidones, or low or non ozone depleting halogenated hydrocarbons. These mixtures are useful in a variety of solvating, vapor degreasing, photoresist stripping, adhesive removal, aerosol, cold cleaning, and solvent cleaning applications including defluxing, dry cleaning, degreasing, particle removal, metal and textile cleaning. In particular, the composition comprising the dichloroethylene compounds and alkoxy-substituted perfluoro compounds that contain six carbon atoms (HFE6C), with highly fluorinated materials to retard flammability and/or other enhancement agents that improve and enhance the properties of the mixture can be used to replace highly ozone depleting materials such as chlorofluorocarbons, methyl chloroform, hydrochlorofluorocarbons or chlorinated solvents. In addition these mixtures will be more robust cleaning agents versus present art that uses HFC's and HFE's.
In the novel cleaning compositions of the present invention, dichloroethylene materials include 1,1-dichloroethylene, 1,2-cis-dichloroethylene and 1,2-trans-dichloroethylene.
Alkoxy-substituted perfluoro compounds that contain six carbons (HFE6C) include all isomers of perfluorobutane ethyl ether (C4F9—O—C2H5) and all isomers of perfluoropentane methyl ether (C5F11—O—CH3).
Highly fluorinated materials used in this invention are compounds of the formula CaFbHcXd where a is an integer from 2 to 8, b is an integer greater than a but less than 2a+2, d is 0, 1, or 2, and c is less than or equal to 2a+2−b−d. X can be O, N, halogen, or Si, in any possible combination as long as the number of F atoms exceeds the number of H atoms in the molecule. Throughout this specification and claims, by “halogen” is meant Cl, Br, and I.
Suitable enhancement agents are one or more of the following materials: alcohols, esters, ethers, cyclic ethers, ketones, alkanes, aromatics, amines, siloxanes, terpenes, dibasic esters, glycol ethers, pyrollidones, or low-or non ozone depleting-halogenated hydrocarbons.
The addition of the fluorinated compounds to the mixture will reduce and/or eliminate the flammability measured as the closed and/or open cup flash points of the mixture. In addition the proper selection of the materials in the mixture may create an azeotrope or azeotrope-like blend which is desirable. Furthermore, those skilled in the art would be aware of other additives such as surfactants, colorants, dyes, fragrances, indicators, inhibitors, and buffers as well as other ingredients which modify the properties of the mixture.
The dichloroethylene component of the mixture contains effective amounts of 1,1-dichloroethylene, 1,2-cis-dichloroethylene and 1,2-trans-dichloroethylene. They are usable either singly or as a mixture of two or more. Among the most preferred are 1,2-trans- and 1,2-cis-dichloroethylene.
The alkoxy-substituted perfluoro compounds that contain six carbon atoms (HFE6C) are all isomers of perfluorobutane ethyl ether (C4F9—O—C2H5) and perfluoropentane methyl ether (C5F11—O—CH3). Examples of these compounds are n-perfluorobutane ethyl ether, iso-perfluorobutane ethyl ether, tert-perfluorobutane ethyl ether, n-perfluoropentane methyl ether, 2-trifluoromethyl perfluorobutyl 1-methyl ether, 2-trifluoromethyl perfluorobutyl 2-methyl ether, 2-trifluoromethyl perfluorobutyl 3-methyl ether, 2-trifluoromethyl perfluorobutyl 4-methyl ether, 2,2-trifluoromethyl perfluoropropyl 1-methyl ether.
The highly fluorinated materials of this invention are compounds of the formula CxFyHzXa where x is 2-8, y>x and z<y; and a can be 0 or greater. X can be O, N, halogen, or Si, in any possible combination as long as the number of F atoms exceeds the number of H atoms in the molecule. Examples of suitable fluorinated materials are tetrafluoroethane, pentafluoroethane, perfluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, perfluoropropane, hexafluorobutane, heptafluorobutane, octafluorobutane, nonafluorobutane, perfluorobutane, heptafluoropentane, octafluoropentane, nonafluoropentane, decafluoropentane, undecafluoropentane, perfluoropentane, octafluorohexane, nonafluorohexane, decafluorohexane, undecafluorohexane, dodecafluorohexane, tridecafluorohexane, and perfluorohexane. Other commercially available fluorinated compounds are: 3-chloro-1,1,1-trifluoropropane (HCFC-253fb); 1,1,1,3,3,5,5,5-octafluoropentane (HFC-458mfcf); 4-trifluoromethyl-1,1,1,2,2,3,3,5,5,5-decafluoropentane (HFC-52-13); 4-trifluoromethyl-1,1,1,2,2,5,5,5-octafluoropentane (HFC-54-11); 4-trifluoromethyl-1,1,1,2,2,3,5,5,5-nonafluoropentane (HFC-53-12); 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC-43-10mee) 1,1,1,2,2,3,3,4,4,5,6-undecafluorohexane (HFC-54-11qe); 1,1,2,2,3,3,4,4-octafluorobutane (HFC-338pcc); 1,1,1,2,2,3,3,4,4-nonafluorobutane-4-methyl ether (HFE-7100); 1,1,1,2,2,3,4,4,4-nonafluoroisobutane-3-methyl ether (HFE-7100); 1,1,1,2,2,3,3,4,4-nonafluorobutane-4-ethyl ether (HFE-7200); 1,1,1,2,2,3,4,4,4-nonafluoroisobutane-3-ethyl ether (HFE-7200); 1,1,2,2,3,3,4,5-octafluorocyclopentane; pentafluoroethane (HFC-134); dichloro-trifluoroethane (HCFC-123); trichloro-tetrafluoropropane (HCFC-224); dichloro-pentafluoropropane (HCFC-225); dichloro-tetrafluoropropane (HCFC-234); chloro-pentafluoropropane (HCFC-235); chloro-tetrafluoropropane (HCFC-244); chloro-hexafluoropropane (HCFC-226); pentachloro-difluoropropane (HCFC-222); tetrachloro-trifluoropropane (HCFC-223); trichloro-trifluoropropane (HCFC-233) pentafluoropropane (HFC-245) nonafluorobutylethylene (PFBET) and 1-bromopropane. Fluoroalcholos such as trifluoroethanol can also be used. They can be used either singly or as a mixture of two or more. Among the most preferred are HFE-7100, HFC 43-10, HCFC-225, PFBET, 1-bromopropane and octafluorocyclopentane.
Other compounds may be added to the mixture to vary the properties of the cleaner or solvent to fit various applications. The addition of these other compounds may also assist in the formation of useful azeotropic compositions. An azeotropic composition is defined as a constant boiling mixture of two or more substances that behaves like a single substance. Azeotropic compositions are desirable because they do not fractionate upon boiling. This behavior is desirable because mixtures may be used in vapor degreasing equipment and or the material may be redistilled.
Since achieving a perfect azeotrope is not practical in industrial use, all mixtures are described as “azeotrope-like”. The term “azeotrope-like composition” means a constant boiling or substantially constant boiling mixture of two or more substances that behave as a single substance, which therefore can distill without substantial compositional change. Constant boiling compositions, which are characterized as “azeotrope-like” will exhibit either a maximum, or minimum boiling point compared to non azeotropic mixtures of two substances at a given pressure.
As used herein, the terms azeotrope, azeotrope-like and constant boiling are intended to mean also essentially azeotropic or essentially constant boiling. In other words, included within the meaning of these terms are not only the true azeotropes, but also other compositions containing the same components in different proportions, which are true azeotropes or are constant boiling at other temperature and pressure. As is well recognized in this art, there is a range of compositions which contain the same components as the azeotrope, which will not exhibit essentially equivalent properties for cleaning, solvating and other applications, but will exhibit essentially equivalent properties as the true azeotropic composition in terms of constant boiling characteristics or tendency not to separate or fractionate on boiling.
The alcohol useful as an enhancement agent is of the formula CxHyOz where x is 1 to 12, preferably 1 to 8, more preferably 1 to 6, y is greater than x but less than 2x+2, and z is 1 to 3 provided that at least one O is a hydroxyl oxygen. Examples of these alcohols are methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, n-butyl alcohol, 2-butyl alcohol, t-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, allyl alcohol, 1-hexanol, 2-hexanol, 3-hexanol, 2-ethyl hexanol, 1-octanol, 1-decanol, 1-dodecanol, cyclohexanol, cyclopentanol, benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, bis-hydroxymethyl tetrahydrofuran, ethylene glycol, propylene glycol, and butylene glycol. They can be used either singly or in the form of a mixture of two or more. Among the most preferred are methanol, ethanol, n-propanol, isopropanol, and tert butyl alcohol.
The ester useful as an enhancement agent is of the formula R1—COO—R2 where R1 and R2 could be the same or different, R1 is hydrogen, C1-C20 alkyl, C5-C6 cycloalkyl, benzyl, furanyl or tetrahydrofuranyl, preferably C1 to C8 alkyl, more preferably C1 to C4 alkyl; R2 is C1-C8 alkyl, preferably C1 to C4 alkyl, C5-C6 cycloalkyl, benzyl, phenyl, furanyl or tetrahydrofuranyl. Examples of these esters are methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl formate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl formate, propyl acetate, propyl propionate, propyl butyrate, butyl formate, butyl acetate, butyl propionate, butyl butyrate, methyl soyate, isopropyl myristate, propyl myristate, and butyl myristate. Among the most preferred are methyl formate, methyl acetate, ethyl acetate and ethyl formate.
The ether useful as an enhancement agent is of the formula R3—O—R4 where R3 is C1-C10 alkyl or alkynl, C5-C6 cycloalkyl, benzyl, phenyl, furanyl or tetrahydrofuranyl, R4 is C1-C10 alkyl or alkynyl, C5-C6 cycloalkyl, C1-C4 ether, benzyl, phenyl, furanyl or tetrahydrofuranyl. Examples of these ethers are ethyl ether, methyl ether, propyl ether, isopropyl ether, butyl ether, methyl tert butyl ether, ethyl tert butyl ether, vinyl ether, allyl ether, methylal, ethylal and anisole. In the composition listed R3 and R4, which can be the same or different, can be C1 to C10 alkyl or alkynyl, preferably C1 to C6 alkyl or alkynyl, more preferably C1 to C4 alkyl. Among the most preferred are isopropyl ether, methylal and propyl ether.
The preferred cyclic ethers are: 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran (THF), methyl THF, dimethyl THF and tetrahydropyran (THP), methyl THP, dimethyl THP, ethylene oxide, propylene oxide, butylene oxide, amyl oxide, and isoamyl oxide. Most preferred is THF.
The ketone component of the mixture is of the formula: R5—C═O—R6 where R5 is C1-C10 alkyl or alkynyl, C5-C6 cycloalkyl, benzyl, furanyl or tetrahydrofuranyl, R6 is C1-C10 alkyl, C5-C6 cycloalkyl, benzyl, phenyl, furanyl or tetrahydrofuranyl. Examples of these ketones are acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, and methyl isobutyl ketone. R5 and R6, which can be the same or different, can be are, preferably C1 to C6 alkyl, more preferably C1 to C4 alkyl. Among the most preferred are acetone, methyl ethyl ketone, 3-pentanone and methyl isobutyl ketone.
The alkane useful as an enhancement agent is of the formula: CnHn+2 where n is 1-20, or C4-C20 cycloalkanes. Examples of these alkanes are butane, methyl propane, pentane, isopentane, methyl butane, cyclopentane, hexane, cyclohexane, isohexane, heptane, methyl pentane, dimethyl butane, octane, nonane and decane. n is preferably 4 to 9, more preferably 5 to 7. Among the most preferred are cyclopentane, cyclohexane, hexane, methyl pentane, and dimethyl butane.
The aromatic compound useful as an enhancement agent is of the formula: C6Hn—X6−n where n is 0 to 6. X can be hydroxyl, halogen or any of the alkane, alcohol, ether groups listed above. Examples of these aromatics are benzene, toluene, xylene, ethylbenzene, cumene, mesitylene, hemimellitine, pseudocumene, butylbenzene, phenol and benzotrifluoride. Among the most preferred are toluene, xylene and mesitylene.
The amine useful as an enhancement agent is of the formula: NR7R8R9 where R7, R8 and R9 can be hydrogen, hydroxyl, C1-C10 alkyl, C1-C10 alcohol. R7, R8 and R9 can all be the same or independently different. Examples of these amines are methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, di-isopropylamine, tri-isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, ethanolamine, diethanolamine, triethanolamine, amino methyl propanol and hydroxylamine. Most preferred are butylamines and triethylamine.
The siloxane useful as an enhancement agent is a volatile methyl siloxane. Three examples of these are hexamethyl disiloxane, octamethyl trisiloxane and decamethyl tetrasiloxane. Most preferred is hexamethyl disiloxane.
The terpene useful as an enhancement agent contains at least one isoprene group of the general formula:
The molecule may be cyclic or multicyclic. Preferred examples are d-limonene, pinene, terpinol, turpentine and dipentene.
The dibasic ester which can be used as an enhancement agent is of the formula: R10—COO—R11—COO—R12 where R10 is C1-C20 alkyl, C5-C6 cycloalkyl, benzyl, furanyl or tetrahydrofuranyl, R11, is C1-C20 alkyl, C5-C6 cycloalkyl, benzyl, phenyl, furanyl or tetrahydrofuranyl, R12 is C1-C20 alkyl, C5-C6 cycloalkyl, benzyl, furanyl or tetrahydrofuranyl. Examples of these dibasic esters are dimethyl oxalate, dimethyl malonate, dimethyl succinate, dimethyl glutarate, dimethyl adipate, methyl ethyl succinate, methyl ethyl adipate, diethyl succinate, diethyl adipate. In the formula, R10, R11, and R12, which can be the same or different, are preferably C1 to C6 alkyl or alkynyl, more preferably C1 to C4 alkyl. Among the most preferred are dimethyl succinate, and dimethyl adipate.
The glycol ether component which can be used as an enhancement is of the formula: R13—O—R14—O—R15 where R13 is C2-C20 alkyl, C5-C6 cycloalkyl, benzyl, furanyl or tetrahydrofuranyl, R14 is C1-C20 alkyl, C5-C6 cycloalkyl, benzyl, phenyl, furanyl or tetrahydrofuranyl, R15 is hydrogen or an alcohol as defined above. Examples of these glycol ethers are ethylene glycol methyl ether, diethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol ethyl ether, ethylene glycol propyl ether, diethylene glycol propyl ether, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, dipropylene glycol, dipropylene glycol methyl ether, propylene glycol propyl ether, dipropylene glycol propyl ether, methyl methoxybutanol, propylene glycol butyl ether, and dipropylene glycol butyl ether. Among the most preferred are propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol, methyl methoxybutanol, dipropylene glycol butyl ether and diethylene glycol butyl ether.
The pyrrolidone enhancement agent is substituted in the N position of the pyrrolidone ring by hydrogen, C1 to C8 alkyl, or C1 to C8 alkanol. Examples of these pyrrolidones are pyrrolidone, N-methylpyrrolidone, N-ethyl pyrrolidone, N-propyl pyrrolidone, N-hydroxymethyl pyrrolidone, N-hydroxyethyl pyrrolidone, and N-hexyl pyrrolidone. Among the most preferred are N-methylpyrrolidone and N-ethyl pyrrolidone.
The halogenated hydrocarbon enhancement agent is of the formula: R16—Xy where R16 is C1-C20 alkyl, C4-C10 cycloalkyl, C2-C20 alkenyl benzyl, phenyl, fluoroethyl, and X is chlorine, bromine fluorine or iodine and y is not 0, and the Ozone Depletion Potential (ODP) of the molecule <0.15. Examples of these chlorinated materials are methyl chloride, methylene chloride, ethyl chloride, dichloro ethane, propyl chloride, n-propyl bromide, isopropyl chloride, propyl dichloride, butyl chloride, isobutyl chloride, sec-butyl chloride, tert-butyl chloride, pentyl chloride, and hexyl chloride. Among the most preferred are methylene chloride, and n-propyl bromide.
The inventive compositions are intended to be used in a similar manner as CFC's and chlorinated solvents, which have been widely used in the past in cleaning applications. These mixtures may be used in various techniques of cleaning which would be apparent to one skilled in the art such as spraying, spray under immersion, vapor degreasing/cleaning, immersion at either the boiling point or below the boiling point, wiping with cloths and brushes, immersion with ultrasonics, immersion with tumbling and spraying into air. These techniques were used to clean hard surfaces of items and were also used to clean textiles.
The compositions are also intended to be used in a similar manner as CFC's and chlorinated solvents, which have been widely used in past solvating applications. These mixtures may be used as a solvent in adhesives, paints, chemical processes, and other applications in which the solubility parameter of the solvent dissolved the solid or liquid, and/or exhibited appropriate volatility for the application.
The key to the success of these mixtures as solvents and cleaning agents is the fact that it is desirable for these mixtures to be formulated to have no flash point. This is important because it allows the solvent to be used safely without the threat of flammability as was found in similar solvents, which had the same volatility. As such the highly fluorinated material described becomes necessary in most mixtures to retard the closed cup flash point of the mixture.
Although not required it is desirable that the mixture forms an azeotrope-like mixture. This is desirable because it allows for a consistent flash point and allows the product to be distilled and recovered.